In related art, an image forming apparatus includes a configuration that intermittently transmits a driving force from a drive source. PTL 1 discloses a drive transmission device for intermittently driving a sheet feed roller as a driven member.
The drive transmission device in PTL 1 includes a driving gear constantly rotated by a motor, and a driven gear that meshes with the driving gear and rotates, and hence that transmits a driving force to the sheet feed roller. The driven gear has a toothless portion. Then, by retaining the driven gear with a claw, the driven gear is stopped at a position, at which the toothless portion faces the driving gear, and the drive transmission from the driving gear to the driven gear is cut off. By releasing the retention on the driven gear with the claw, the driven gear meshes with the driving gear again and is rotated. With this configuration, the sheet feed roller is intermittently driven.
Also, in PTL 1, when the driven gear is rotated to the position, at which the toothless portion faces the driving gear for stopping the driven gear, or when the stopped driven gear is rotated to the position, at which the driven gear meshes with the driving gear again, the toothless portion of the driven gear faces the driving gear. Owing to this, it is difficult to obtain a rotational force from the driving gear and rotate the driven gear. Therefore, in PTL 1, the driven gear is rotated by an elastic force of a tension spring or a leaf spring.